Synthesis, structure and properties of 2D lanthanide coordination polymers based on N-heterocyclic arylpolycarboxylate ligands.

The reaction of 3-(2,4-dicarboxyphenyl)-2,6-pyridinedicarboxylic acid (H4dppd) with rare earth nitrates under hydrothermal conditions generated a series of new two-dimensional (2D) coordination polymers, namely {[La(Hdppd)(H2O)2·(H2O)2]n (1), [Ln2(Hdppd)2(H2O)4·(H2O)3]n [Ln = Sm (2), Eu (3)] and [Ln(Hdppd)(H2O)3·H2O]n [Ln = Gd (4), Tb (5), Dy (6), Ho (7), Er (8)] [Hdppd = 3-(2,4-dicarboxyphenyl)-2,6-pyridinedicarboxylic trivalent anion]}. The complexes were characterized by X-ray single-crystal diffraction, infrared spectroscopy, elemental analysis and thermogravimetric analysis. Luminescence spectroscopy of 3 and 5 showed bright red and green luminescences due to the 4f(n)-4f(n) transitions in Eu(3+) and Tb(3+) respectively, although the luminescence lifetime is shortened by non-radiative decay due to the presence of coordinating water molecules. The magnetic properties of 2-8 were measured and discussed. Compound 6 exhibits frequency dependent out-of-phase signals, and ferromagnetic coupling exists in 8.

Solvent-regulated assemblies of 1D lanthanide coordination polymers with the tricarboxylate ligand.

Solvothermal reactions of the tricarboxylic acid ligand, biphenyl-3,3',5-tricarboxylic acid (H3bpta), and rare earth nitrate (Ln(NO3)3·6H2O) in the presence of KOH or DMF produced eight 1D linear coordination polymers, namely, [La(bpta)(H2O)5·(H2O)3]n (), [Pr(bpta)(H2O)5·(H2O)2.5]n (), [Nd(bpta)(H2O)5·(H2O)1.75]n (), [Sm(bpta)(H2O)5·(H2O)0.5]n () and [Ln(bpta)(DMF)(H2O)3·(H2O)]n [Ln = Eu (), Gd (), Tb (), Dy ()]. The 1D chain further assembles into a 3D supramolecular network structure through hydrogen bonds and π-π stacking among chains. Complexes and display the typical emission spectra for lanthanide-centred luminescence. The optical properties of were analysed in detail and coincide well with the structural properties. The influence of temperature on the luminescence lifetime of has been studied and different non-radiative decay paths have been discussed. The magnetic properties show that and exhibit strong spin-orbit coupling, while weak antiferromagnetic coupling exists in .

Preparation of Eu3+-Y3+ coactivating Na+ based red-emitting luminous materials for light-emitting diodes and investigation of its characteristics.

By solid-state reaction and doping, a series of red-emitting phosphors Na(x)Y(0.92-x/3)(MoO(4))(y)(WO(4))(1-y)O(0.5) : zEu(3+) have been synthesized. Through optimization of the process conditions and photoluminescent analysis, one type of red emission is obtained that matches nicely with ultraviolet light-emitting diode (UV-LED) chips.

Instense red phosphors for UV light emitting diode devices.

Ca(x)Sr1-x-1.5y-0.5zMoO4:yEu3+ zNa+ red phosphors were prepared by solid-state reaction using Na+ as charge supply for LEDs (light emitting diodes). The content of charge compensator, Ca2+ concentration, synthesis temperature, reaction time, and Eu3+ concentration were the keys to improving the properties of luminescence and crystal structure of red phosphors. The photoluminescence spectra shows the red phosphors are effectively excited at 616 nm by 311 nm, 395 nm, and 465 nm light. The wavelengths of 395 and 465 nm nicely match the widely applied emission wavelengths of ultraviolet or blue LED chips. Its chromaticity coordinates (CIE) are calculated to be x = 0.65, y = 0.32. Bright red light can be observed by the naked eye from the LED-based Ca0.60Sr0.25MoO4:0.08Eu3+ 0.06Na+.

A red-emitting phosphor and its luminescent properties.

Under 616 nm monitoring, excitation peaks at 395, 465, and 535 nm were observed for the red-emitting phosphor Li(0.3)Y(0.82)Mo(0.1)W(0.9)O(4+delta): 0.08Eu(3+) (LYMW), which was synthesized using the solid-state method. Particularly in the range of 250 to 420 nm, excited peaks can be assigned to the transitions of O(2-)-->Mo(6+)/W(6+)/Eu(3+) and four sharp peaks can be assigned to the 4f-4f transition of Eu(3+) (approximately 360 nm from the (7)F(0)-->(5)D(4) transition, approximately 380 nm from the (7)F(0)-->(5)L(7) transition, approximately 395 nm from the (7)F(0)-->(5)(L6) transition, and approximately 415 nm from the (7)F(0)-->(5)D(3) transition).